For the past 6 weeks a friend of mine has been bringing his 4 month old female mini terrier mix over to help socialize Dexter and his puppy. They even sleep together. Last week he came over after a 2 week absence. My shih tzu female was in heat and started barking at his terrier, my poodle mix joined in and so did Dexter. I had to take my female to another room to calm the dogs down. I let Dexter and the terrier outside alone where he proceeded to smell her and started to play as usual. Did he not remember her? How often does she have to come over so that he does recognize her?